http://ecg.bidmc.harvard.edu/maven/mavenmain.asp
ECG wave maven. Classic ECG site. Very good self-assesment tool and ECG bank for reveiwing multiple presentations of various pathologies. Very good tool to copy and paste ECG's into your powerpoint presentations.

http://www.ccmtutorials.com/
Critical Care Medicine tutorial. Must read for all interns prior to starting CCU/ICU. Excellent section on ventilators and Respiratory pathology. Great review for seniors.